Manifold for fountain-type liquid dispenser

ABSTRACT

In an electrostatic printing machine, a manifold for applying liquid developer to an adjacent recording element comprises an elongated body of electrically conductive material. An exit slit, formed in the top surface, serves to direct the liquid developer to the recording element. A plurality of spaced-apart ridges extend upwardly from the top surface, adjacent side edges thereof, and form a plurality of spaced-apart slots between adjacent ridges, respectively, so that liquid developer that is pumped through the exit slit can flow off the top surface via the slots, in a direction perpendicular to the exit slit.

United States Patent Giaimo, Jr.

[54] MANIFOLD FOR FOUNTAIN-TYPE LIQUID DISPENSER [72] Inventor: EdwardCharles Glalmo, Jr., Princeton,

[73] Assignee: RCA Corporation [22] Filed: Mar. 26, 1970 [21] Appl. No.:22,911

[52] US. Cl. ..l18/637, l18/DIG. 23, 118/429 [51] Int. Cl. ..G03g 13/00,[58] Field of Search ..1 18/637, 637 LX, DIG. 23, 612, 118/300, 410,429, 400; 117/175, 37 LX, 222/579; 355/10; 228/36, 37

[56] References Clted UNITED STATES PATENTS 3,407,786 10/1968 Beyer'eta1 ..1 18/637 3,342,164 9/1967 Lewis ..118/637 3,507,252 4/1970 Leedom..118/637 2,956,494 10/1960 Tyler et a1; 1 18/637 LX 1 May 23, 19723,303,983 2/ 1967 Patrick et al ..228/37 3,119,363 l/l964 Rieben..ll3/l26 3,081,535 3/1963 Lincoln. ..228/37 3,536,243 10/1970 Higgins"...228/37 3,482,755 12/1969 Racciti ..228/37 Primary Examiner-MorrisKaplan Assistant Examiner-Leo Millstein Attomey-Glenn H. Bruestle [57]ABSTRACT ln an electrostatic printing machine, a manifold for applyingliquid developer to an adjacent recording element comprises an elongatedbody of electrically conductive material. An exit slit, formed in thetop surface, serves to direct the liquid developer to the recordingelement. A plurality of spacedapart ridges extend upwardly from the topsurface, adjacent side edges thereof, and form a plurality ofspaced-apart slots I between adjacent ridges, respectively, so thatliquid developer that is pumped through the exit slit can flow off thetop surface via the slots, in a direction perpendicular to the exitslit.

8 Clalns, 5 Drawing Figures PATENTEDHAY 23 I972 SHEET 1 0F 2 MJWMANIFOLD FOR FOUNTAIN-TYPE LIQUID DISPENSER BACKGROUND OF THE INVENTIONThis invention relates generally to an improved manifold, and moreparticularly to an improved manifold for applying a liquid to ahorizontal surface. The improved manifold is particularly useful in anelectrostatic printing system for applying electroscopic liquiddeveloper to the surface of a moving electrophotographic recordingelement to develop an electrostatic charge pattern thereon.

The manifold of the present invention is an improved structure for usewith a fountain-type liquid dispenser of the type described in US. Pat.application, Ser. No. 640,564, filed May 23, 1967, for M. A. Leedom, andentitled Combination of a Container for a Liquid and Means forDispensing the Liquid, now US. Pat. No. 3,507,252, issued on Apr. 21,1970." In the prior-art liquid dispenser, an exit slit for a manifold isformed between two parallel and horizontal strips of metal, each striphaving parallel sides and both strips functioning as a bias electrodewhen connected to a source of voltage. While the priorart manifold issuitable for certain applications, it has been found that when liquiddeveloper, comprising toner particles dispersed in a carrier liquid, ispumped through the exit slit, the liquid developer does not always flowfreely and directly from the exit slit to the nearest side edges of thebias electrode. This is believed to result from the interaction betweenthe surface tension of the liquid developer and the nonuniform wettingof the bias electrode. Consequently, the liquid developer sometimesspills over the edges of the bias electrode only at random points alongits length, causing transverse eddy currents to form in the liquiddeveloper. This action tends to concentrate the toner particles of theliquid developer at those points along the edges of the bias electrodewhere the liquid developer spills over. Such action may result in anuneven application of the liquid developer to a recording element to bedeveloped, causing uneven development and I SUMMARY OF THE INVENTION Theimproved manifold for applying a liquid to a surface comprises a bodythat has a surface with an exit slit formed in a portion thereof. Meansare disposed along each side of the exit slit to cause liquid dispensedfrom the exit slit to flow laterally therefrom to, and over, oppositeedges of the top surface at a multiplicity of points thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional drawing,partly schematic, of a combination of a container for a liquid and meansfor dispensing the liquid, showing a cross-section of the improvedmanifold, taken along the line 11 in FIG. 2, for applying the liquid toa moving electrophotographic recording element;

FIG. 2 is an enlarged, perspective view of the improved manifold shownin FIG. 1;

FIG. 3 is an enlarged, perspective view of another embodiment of theimproved manifold;

FIG. 4 is a fragmentary, enlarged, perspective view of still anotherembodiment of the improved manifold; and

FIG. 5 is an enlarged perspective view of a further embodiment of theimproved manifold.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis shown an electrophotographic recording system 10 forelectrostatically charging, exposing, and developing anelectrophotographic recording element 12 with the aid of a fountain-typeliquid dispenser 14 for an electroscopic liquid developer 16. With theexception of an improved manifold 20 for the fountain-type liquiddispenser 14, the operation of the electrophotographic recording system10 is described in detail in the aforementioned US. Pat. application,Ser. No. 640,5 64.

Briefly, the recording element 12, comprising a substrate 22 of paperand a photoconductive layer 24 thereon, is electro statically charged indarkness by double corona discharge devices 26 and 28 connected to asuitable source of unidirectional voltage. The electrostatically chargedphotoconductive layer 24 is exposed by an image on the face of acathode-ray tube 30, the cathode-ray tube 30 being connected to asuitable signal source 32, such as a character generator well known inthe art. The recording element 12 with an electrostatic latent imagethereon, resulting from the exposure of the charged photoconductivelayer 24, is moved in the directions of the arrows 34 and 36 by anysuitable means, adjacent to the manifold 20 where it is developed by theelectroscopic liquid developer 16. The developed image which may bedried by any suitable means known in the art represents a reproductionof the exposure image provided by the cathode-ray tube 30.

The operation of the fountain-type liquid dispenser 14, with theexception of the improved manifold 20, is also fully explained in theaforementioned US. Pat. application, Ser. No. 640,564. Briefly, theliquid developer 16, in a reservoir 38, is pumped by a pump 40 throughsuitable conduits to a standpipe 42 and to the manifold 20, indirections indicated by arrows representing liquid developer flow. Theliquid developer 16 is returned from both the standpipe 42 and themanifold 20 through suitably placed return conduits, as indicated by thearrows showing the directions of flow of the liquid developer 16. Thestandpipe 42 communicates with the manifold 20 and serves to provide aconstant pressure to the liquid developer 16 emerging from the manifold20.

The improved manifold 20, shown in FIGS. 1 and 2, comprises an elongatedbody which may be either a solid metal, such as stainless steel, forexample, or a body 44 of plastic material covered with a cover 46 ofmetal, such as stainless steel. The improved manifold 20 is secured tothe top surface 47 of the fountain-type liquid dispenser 14, as at 49,by any suitable adhesive or fastening means. The cover 46 of theimproved manifold 20 comprises electrically conductive material becauseit functions as a bias electrode, the cover 46 being connected to thenegative terminal of a variable voltage source 48 by a conductor 50. Anelectrically conductive roller 52, for disposing a horizontal surface ofthe recording element 12 adjacent to the manifold 20 for development, isconnected to the positive terminal of the voltage source 48 through aconductor 54. The polarity of these connections depends on the charge onthe recording element 12, the polarity of the toner particles in theliquid developer 16, and whether direct orreversal prints are desired.The conductor 50 is attached to the cover 46 by any suitable means, as,for example, solder.

The manifold 20 comprises a planar top surface 56 formed with anelongated exit slit 58 in a portion adapted to be disposed in ahorizontal position. The exit slit 58 extends in a directionintermediate opposite ends 60 and 62 of the manifold 20 and issubstantially parallel to opposite sides 64 and 66 of the manifold 20.The exit slit 58 extends through the top surface 56 and serves tocommunicate with the conduits of the fountain-type liquid dispenser 14leading from the pump 40 to direct the liquid developer 16 onto thephotoconductive surface 24 of the recording element 12. The portion ofthe top surface 56 in which the exit slit 58 is formed is adapted to bepositioned in a horizontal plane so that it may direct the liquiddeveloper 16 onto a horizontal portion of the recording element 12 thatis disposed adjacent to, and slightly spaced from, the exit slit 58 bythe roller 52.

Means are provided to cause the liquid developer 16 that emerges throughthe exit slit 58 to flow evenly over the surface 56 and to spill overopposite edges 68 and 70, formed by the top surface 56 and the oppositesides 64 and 66, respectively. To this end, a plurality of regularlyspaced-apart fingers 72, extending laterally from a strip 74, areadhered to the opposite sides 64 and 66 by any suitable means, such asscrews 73 and 75, to provide a plurality of regularly spaced-apartridges 76 extending upwardly from the top surface 56 along the oppositeedges 68 and 70. The upper portions of the fingers 72 are bent inwardlytoward the exit slit 58 to provide the ridges 76. Regularly spaced-apartslots 78, formed by adjacent ridges 76, provide regularly spacedchannels through which the liquid developer 16 that emerges through theexit slit 58 can spill over. Thus, by providing the plurality ofregularly spaced slots 78, means are provided for the liquid developer16 to spill over at a plurality of regularly spaced points along theopposite edges 68 and 70, whereby to provide a substantially even flowof liquid developer 16 over the top surface 56 in a directionsubstantially perpendicular to the length of the exit slit 58.

The width of each finger 72 may be in the range between 0.020 and 0.060inch and the width of the slots between adjacent ridges 76 may be in therange between 0.010 and 0.030 inch. The thickness of the fingers 72 maybe in the range between 0,005 and 0.015 inch and, hence, each extends adistance in the range between 0.005 and 0.015 inch above the top surface56 of the manifold 20. This structure has the advantage of causing ahead of liquid, larger than would otherwise be possible, to form on thetop surface 56 for developing the recording element 12. The width of themanifold 20 is about one-half inch and its length about 6 inches. Thesemeasurements, however, are merely illustrative of one embodiment of theimproved manifold 20 and are not to be considered in a limiting sense.

Referring now to FIG. 3, there is shown a manifold structure 80, anotherembodiment of the improved manifold 20. The manifold structure 80comprises an elongated body 82 either entirely of an electricallyconducting material or of a plastic material covered with a cover ofelectrically conducting material and secure to the top surface 47 of thefountain-type liquid dispenser 14. The manifold structure 80 is formedwith an elongated exit slit 84 in a portion of a top concave surface 85adapted to be disposed in a horizontal position, and extends in adirection intermediate ends 86 and 88 of the body 82. The exit slit 84communicates with the pump 40 in the manner described for the manifold20. A plurality of regularly spaced slots 90 are formed along theopposite side edges 92 and 94 of the concave surface 85 on oppositesides of the exit slit 84. The conductor 50 is connected to the end 86of the body 82 by a screw 95.

The radius of curvature of the top concave surface 85, which functionsas a reservoir, is slightly greater than the radius of curvature of thecylindrical surface of the roller 52. Since a typical recording elementmay have a thickness of about 3 mils, and the roller 52 may have aradius of curvature of about one-halfinch, the radius of curvature ofthe top concave surface 85 should be about 0.050 inch greater than theradius of curvature of the roller 52, the top concave surface 85 beingspaced a distance of about 0.050 inch from the roller 52. The slots 90have a width in the range between 0.010 and 0.030 inch, and ridges 96,extending between the slots 90, have a width in the range between 0.020and 0.060 inch. The foregoing dimensions are merely illustrative and arenot to be construed in a limiting sense. The ridges 96 extend upwardlyfrom the portion of the top surface 85 that defines the exit slit 84 sothat liquid pumped through the exit slit 84 can flow over the topsurface 85 and off therefrom through the spaced-apart slots 90.

In operation, the manifold structure 80, as part of the fountain-typedispenser 14, is disposed with its exit slit 84 horizontally adjacentto, but slightly spaced from, the horizontal portion of the recordingelement 12, the latter being positioned opposite the exit slit 84 by theroller 52. Liquid developer 16 pumped through the exit slit 84 by thepump 40 tends to form a bead of liquid developer 16 on the concavesurface 85, but the regularly spaced-apart slots 90 provide spill overpoints for the bead. Hence, the liquid developer 16 emerging from theexit slit 84 flows laterally over the concave surface 85, in a directionsubstantially perpendicularly from the exit slit 84.

Referring now to FIG. 4, there is shown a manifold structure 100. Themanifold structure 100 comprises an elongated body 102 either entirelyof an electrically conducting material or of a plastic material coveredwith a cover of electrically conducting material. The manifold structure100 is formed with an elongated slit 104 in a portion of a top surface106.

Means are provided to cause liquid developer that emerges through theslot 104 to flow laterally over the surface 106 and to spill overopposite side edges 108 and 110 of the top surface 106. To this end, aplurality of regularly spaced-apart fingers 112, extending upwardly froma strip 114, are adhered to opposite sides 116 and 118 of the manifoldstructure 100. The strips 114 are secured to the sides 116 and 118 byany suitable means, such as by screws, for example. The fingers 112 mayhave a thickness of between 0.005 and 0.015 inch and may extend abovethe top surface 106 a distance of about 0.015 inch.

In operation, the manifold structure 100 functions substan tially thesame as the manifold 20. Liquid developer pumped through the exit slit104 initially tends to form a bead on the surface 106, the beadformation being aided by the extension of the fingers 1 12, acting as adam, above the top surface 106. When the bead of liquid developerbecomes large enough to overcome its surface tension, the liquiddeveloper flows over the edges 108 and 110 through grooves 120, formedbetween the upwardly extending fingers 112. This action tends to providea reservoir of liquid developer on the top surface 106 with a lateralflow of the liquid developer from the exit slit 104 to the grooves 120.

Referring now to FIG. 5, there is shown a manifold structure 130, afurther embodiment of the manifold 20. The manifold structure comprisesan elongated body 132, as of stainless steel, having a top surface 134formed with an elongated exit slit 136 therethrough. A ridge 138, ofrectangular shape, surrounds the exit slit 136, and extends upwardlyfrom the top surface 134 a distance of about 0.015 inch. The ridge 138is coextensive with the side and end vertical walls of the elongatedbody 132.

The surface of the ridge 138 is roughened, as by sandblasting orabrading by any suitable means, to provide it with a plurality of minutegrooves to enhance the wetting by the liquid developer adapted to flowthereover. Perferably the abrading should be in a directionperpendicular to the length of the exit slit 136 so that the minutegrooves formed in the ridge 138 will be substantially perpendicular tothe exit slit 136 too. In operation, liquid developer pumped through theexit slit 136 of the manifold structure 130 first forms a bead, orreservoir, on the top surface 134 and then flows over the ridge 138 at aplurality of points provided by the minute grooves in the roughenedridge 138.

Thus, each of the improved manifolds 20, 80, 100, and 130 provides,along its opposite edges, a controlled rupture of the fluid surfacetension of the liquid developer 16, thereby causing the liquid developerto flow essentially in directions substantially perpendicular to theexit slit and providing an even application of the liquid developer 16to the recording element 12.

I claim:

1. A manifold for applying a liquid to a surface comprising a bodyhaving a generally horizontal top surface,

an exit slit formed through a portion of said top surface,

a plurality of spaced-apart ridges extending upwardly from said portionof said top surface, on opposite sides of, and spaced from, said exitslit, and forming a plurality of spaced-apart slots between adjacentridges, whereby said liquid, when pumped through said exit slit, canflow over said top surface and off therefrom through said slots.

2. A manifold as described in claim 1, wherein said body comprises anelectrically conductive material,

and

said top surface is substantially planar.

3. A manifold as described in claim 1, wherein at least said top surfaceof said body comprises an electrically conductive material, and

said top surface is concave.

4. A manifold as described in claim 1, wherein each of said plurality ofslots extends in a direction transverse to the length of said exit slit.

5. A manifold for applying a liquid to a horizontal surface,

said manifold comprising an elongated body having a generally horizontaltop surface,

said body having a pair of opposite'ends, a pair of opposite sidesbetween said ends, and forming a pair of opposite edges with said topsurface, and an exit slit between'said sides and extending in adirection intermediate said ends, said exit slit extending through aportion of said top surface, the length of said exit slit in said topsurface extending in substantially the same direction as said oppositeedges, and comprising means for directing said liquid to said horizontalsurface, and

a plurality of spaced-apart ridges extending upwardly from said portionof said top surface adjacent said edges, and forming a plurality ofspaced-apart slots between adjacent ridges, respectively.

6. A manifold as described in claim 5, wherein said body compriseselectrically conductive material,

said top surface is substantially planar, and

said plurality of spaced-apart ridges comprise a plurality of metalfingers disposed along said opposite edges and in contact with saidopposite sides and said top surface.

7. A manifold as described in claim 5, wherein said body compriseselectrically conductive material,

said top surface is concave, and

said plurality of spaced-apart slots are formed along said oppositeedges in directions transverse to the length of said exit slit.

8. A manifold as described in claim 5, wherein said body compriseselectrically conductive. material and means for connecting a source ofvoltage thereto, and

said ridges and said slots are spaced from each other in a regularpattern, the width of said ridges being in the range between 0.020 to0.060 inch, and the width of said slots formed between adjacent ridgesbeing in the range between 0.010 and 0.030 inch.

1. A manifold for applying a liquid to a surface comprising a bodyhaving a generally horizontal top surface, an exit slit formed through aportion of said top surface, a plurality of spaced-apart ridgesextending upwardly from said portion of said top surface, on oppositesides of, and spaced from, said exit slit, and forming a plurality ofspaced-apart slots between adjacent ridges, whereby said liquid, whenpumped through said exit slit, can flow over said top surface and offtherefrom through said slots.
 2. A manifold as described in claim 1,wherein said body comprises an electrically conductive material, andsaid top surface is substantially planar.
 3. A manifold as described inclaim 1, wherein at least said top surface of said body comprises anelectrically conductive material, and said top surface is concave.
 4. Amanifold as described in claim 1, wherein each of said plurality ofslots extends in a direction transverse to the length of said exit slit.5. A manifold for applying a liquid to a horizontal surface, saidmanifold comprising an elongated body having a generally horizontal topsurface, said body having a pair of opposite ends, a pair of oppositesides between said ends, and forming a pair of opposite edges with saidtop surface, and an exit slit between said sides and extending in adirection intermediate said ends, said exit slit extending through aportion of said top surface, the length of said exit slit in said topsurface extending in substantially the same direction as said oppositeedges, and comprising means for directing said liquid to said horizontalsurface, and a plurality of spaced-apart ridges extending upwardly fromsaid portion of said top surface adjacent said edges, and forming aplurality of spaced-apart slots between adjacent ridges, respectively.6. A manifold as described in claim 5, wherein said body compriseselectrically conductive material, said top surface is substantiallyplanar, and said plurality of spaced-apart ridges comprise a pluralityof metal fingers disposed along said opposite edges and in contact withsaid opposite sides and said top surface.
 7. A manifold as described inclaim 5, wherein said body comprises electrically conductive material,said top surface is concave, and said plurality of spaced-apart slotsare formed along said opposite edges in directions transverse to thelength of said exit slit.
 8. A manifold as described in claim 5, whereinsaid body comprises electrically conductive material and means forconnecting a source of voltage thereto, and said ridges and said slotsare spaced from each other in a regular pattern, the width of saidridges being in the range between 0.020 to 0.060 inch, and the width ofsaid slots formed between adjacent ridges being in the range between0.010 and 0.030 inch.